Airplane



Sept. 26, 1933- N, RlPPEN 1,928,317

AIRPLANE Filed July 17, 1930 2 Sheets-Sheet 1 duh ATTORNEY Sept. 26, 1933. N. RIPPEN AIRPLANE Filed July 17, 1930 2 Sheets-Sheet 2 I BY INWTPR Patented Sept. 26, 1933 .VUNI'RIED fSTACTES PATENT OFFICE I 1,928,317 amPLANn Nicholas Rippen, New York, N. Y

Application July 1'7, 1930.' Serial No. 468,548

' 9 claims. (Cl. 244-2) The main objects in the design of large ocean going airplanes, otherwise termed seaplanes, other than the usual ones which'are present in all aeronautical design, are to obtain good lateral stability on the water and to dispose the major airfoils at a good height above the water and have the several propellers isolated from spray, and all without sacrificing cleanness of design. One of the most important factors determining the latter'is the partial "or total elimination of external bracing mediums such as struts and wires. It is common knowledge that the interference-phenomenon of struts at their points of attachment to hulls, wings andother parts creates an additional drag equal to and often greater than their drag per se, not to mention the considerable reduction in lift caused by, the ensuing eddyingand distortion in direction of the normal air currents passing over and under the airfoils.

In the present case the water-flotation bodies or hulls are braced by one or more airfoils of compact proportions, suitable consideration being given to staunchness and water-tightness in the airfoils because of their proximity to the water where they are subject to pounding by waves,

particularly in stormy weather, and of course while the airplane is floating on a body of water. The objects, as stated, are all obtained in the present case.

Where a single sturdy lower airfoil, also termed airfoil-brace-member, is used, the question as to the shape, number of units and positions of the water-flotation system is influenced by the opportunityfto eliminate end-losses in the airfoilbrace-member by utilizingtwin hulls at its extremities as well as many other advantageous applications of twin hulls and the key feature of my invention is the combination of a plurality (preferably two) of extremely narrow hulls braced by a relatively deeply cambered, staunch, watertight lower airfoil, or airfoil-brace-member (a plurality of which may be used if desired). This has an advantage over the conventional single centrally located hull with an auxiliary pontoon on each side of it, or the externally unbraced wide dual hull system incorporated in a well known foreign design of flying boat. The favorable efiect of vertical fins at the lateral extremities of the airfoils is well known'but the structural difficulties involved in such extremely narrow, highstructures more than offset the aerodynamic advantages obtained, and has heretofore disfcouraged their adoption. If, however, end loss guards, as they are often termed, are present anyway in the form of necessary hulls, aerodynamic face of the ocean during stormy weather and encountering violent blows from the sides. These shocks, to be safely tolerated, demand a corresponding increase the size and weight of the conventional laterally disposed'pontoons to such a degree as to make the combined weight and size of the pontoons'and the hull approach and possibly surpass that of twin hulls, and for this reason alone the latter system should supplant 7 the conventional single hull system. I

Another important consideration in favor of twin hulls is that, by extending their height to constitute rigid supports for the considerably elevated upper substantially cantilever-type airfoils, their function as end-loss-guards is still further enhanced not: only because of their increased height, but also because of the resultant continuity of' surface created by the upper and lower airfoils joined by the hulls.

In addition, extending the hulls upwardly to form supports for the upper airfoils, permits their employment as supports. for externally unbraced cantilever-type motor nacelles, thus eliminating the usual struts in this instance also. When the height of the hulls permits, space-for a pair of superposed tractor propellers projecting from the front wall of each hull is present, which combined with one pusher propeller on each rear wall, permits six externally unbraced propulsion units on twin hulls, which is probably as many as even the largest planes of the future will require. However, additional propulsion units can be placed over the lower airfoil if desired.

To sum up, besides their normal function of providing flotation bodies, the fourfold applicability oftwin hulls in the role of end-loss guards, effective structures toresist transverse stresses when on water, convenient supports for at least six externally unbraced motor nacelles and rigid supports for considerably elevated major airfoils is a determining reason for theincorporation into the present design of twin hulls.

The use of hulls of small cross section reduces the frontal area and ensuing drag, and their considerablelength prevents porpoising and results in extremely attenuated structures. They therefore require bracing by the lower airfoil close to their bottoms and near their bows and this is the reason for the low forward position of the lower airfoil. If two or more lower airfoils are used instead of the single one shown in the accompanying drawings, positions still. closer to the bows and stems are rendered possible for increased rigidity. In-as-much as the widths of the hulls are determined in part by the total flying load, the dimensions of the lower-airfoils or airfoil-brace-members also have a certain relation to the hull width modified by the number and positions of the members, of course. To

distinguish my lower airfoils from -the airfoil shaped horizontal struts of relatively small size which are very often used-to brace twin majork flotation bodies.

As far as I am aware, no design has ever incorporated airfoil-shaped struts bracing major pontoons wherein the ratio approached one-third (usually the ratio is about one-tenth). The useful aerodynamic qualities of such struts is practically nil in view of their relatively nominal size and they can hardly be considered other than mere structural elements making the same contribution to the general strength of the structure j that any bolt makes. They are struts only.

In the drawings forming part of this application,

Figure 1 is a front elevation of an airplane embodying my invention in the preferred form,

Figure 2 is a sectional elevation thereof taken on the line 2-2 of Figure 3, and

Figure 3 is a plan view.

Having described the salient features of my proposed solution of the problems presented in airplane design, particularly as applied to seaplanes as well as sketching the desiderata commonlysought, I will now proceed to describe in detail the'design of airplane illustrated in the drawings as an example of one embodiment of my invention.

Although a plurality of major lower airfoils or airfoil-brace-members and several hulls can be used without departing from the spirit of my invention, I have selected for illustration an airplane having a single lower airfoil A cambered .sufiiciently to contain passengers and other bulky loads bracing the twin hulls B and B (also termed water-flotation-bodies) at' their lower parts and relatively close to their bows.

The hulls are extended upwardly to constitute rigid supports above the lower airfoil for a pair of major upper airfoils C and C, at their rootportions no portions of which are superposed over the lower airfoil, the several airfoils thus presenting an offset relation with one another as distinguished from the conventional type of monoplane with its airfoil structure disposed substantially in a single horizontal plane. For this reason the term offset-winged seaplane is descriptive of this type.

The longitudinal-normal plane of the juncture of each upper airfoil with its corresponding hull (which is the plane parallel to the plane containing the longitudinal and normal axes of the airplane) is adjacent to the longitudinal-normal plane of the juncture of the nearer extremity of said lower airfoil with the hull mentioned.

The front walls of the bodies B and B support the cantilever type motor nacelles D, E and D, E respectively. Similarly, their rear walls support motor nacelles F and F respectively. I have indicated propellers mounted on the shafts of motors arranged within the several nacelles. These six propulsion units and the cantilever type major upper airfoils all attached to and supported by thetwinhulls, show the practical application of "a system of strutless design mentioned in the preamble; The structures G and G extend rearwardly from the hull to support the horizontal stabilizer H, elevators I, I and I, the vertical fins J, J and J, and the rudders K and K, there being no rudder attached to the central fin J", although a third rudder may be used if desired. Just as the upper airfoils have considerable protection against spray by reason of their height, so

the component parts of the empennage just described are protected in the same manner.

' ,The propellers are protected by the parts of the hulls underneath them with increased height enhancing the protection for the two pusher propellers and the upper tractor propellers.

As my authority for the meanings of the words and expressions in this specification and claims, I refer to Report No. 240, entitled Nomenclature for aeronautics issue-d by the National Advisory Committee 'for Aeronautics, Washington, D. C. Since, however, this reference contains only a functional definition of the word airfoil, which is so prevalent throughout this-specification and the claims, I present the following descriptive definition for the purpose of interpreting this application. Idefine an airfoil as a structure so designed that when projected through the air the relative wind produces in it a useful dynamic reaction. In a cross-sectional view of the plane of the directions of both the wind and the reac-,

tion, the two major surfacesare indicated by an enclosed contour having a single angle (invariably acute) indicating that portion of the structure where the wind departsv from it, consequently termed trailing edge. The terminal of the contour opposed to the angle is curved (on a relatively small radius) and indicates that portion of the structure first to make contact with the wind, consequently commonly termed leading edge, also called entering edge. The straightline connecting the two terminals is invariably at least .triple that of any other straight line. That major surface which faces the direction toward which the reaction acts is termed upper surface and the other is termed lower surface. The upper surface has a mean curvature invariably convex and the lower surface is substantially fiat, convex, concave or compound-curved but whose camber never exceedsthat of the upper surface. My use of the words longitudinal, normal" and lateral in describing directions, dimensions and planes, corresponds to the use of the same terms in the N. A. C. A. Report 240. In it, for instance, the X or longitudinal axis is the one connecting the nose and the tail of an airplane. My use of the adjective "longitudinaP in describing a dimension of the airfoil-brace-member or the case may be. Similarly, theadjective lateral amen reins to the or horizontal direction lies may to grtudinal dimensionfor direction." The Z or vertical axisinthe report is'also calledthe nomisl 'Myuseoi thewords longitudinal-normal plane" will therefore understood to refer to the plane which embraces the longitudinaiand nor mala'xes of theairpiane.

' men mentioning "an-r011" in the-singular in this-specifieation-and in the claims, it "will be' understood that I do so not in the rare-structural but in the usual'aerodynamic sense in which an airfoil system lying substantially ln the same plane is regarded as a single'alrfoilprovided-its structu'ml'eiementsare separated from one another by hulls, fuselages, nacelles or analogous Structures for only nominal distances, as for instance when a fuselage in a mid-wing monoplane separates the airfoil system into two structural entities. Such a structure is not a biplane because of its two wings. It is still a monoplane and is as characteristically so as a parasol-type monoplane in which a single wing is supported over the fuselage at a distance from it by means of a cabane.

Although my invention is particularly applicable to seaplanes I do not desire to limit it to that type of airplane alone. Various changes other than those above mentioned in my description of one embodiment of my invention may be made in the relative positions of some of the parts and details of construction, and mechanical equivalents may be varied without departing from the spirit of my invention as set forth in the following claims.

Having described my invention, what I claim 1. An airplane comprising an airfoil, duplicate means spaced from one another for supporting said airplane when not in flight, an airfoil-bracemember and two substantially enclosed structures joined to and extending downwardly from said airfoil and one of said structures terminating substantially in one of said supporting means,

and the other of said structures in the other of said means, said member bracing said structure directly at their lower parts.

2. A seaplane comprising airfoils, water-flotation-bodies and an airfoil-brace-member all joined together and disposed at a level below that of said airfoils, said brace member having a mean longitudinal dimension at least one third of the mean lateral dimension of one of said bodies and bracing them together.

stantially in said supporting means, said member bracing said structure at the latters lower part to a second structure similar to the one mentioned, said supporting means constituting waterflotation bodies, said brace-member having a mean longitudinal dimension at least one third of the mean lateral dimension of one of said structures.

4. An airplane comprising a lower major air-' foil, a structure whose lower portion is attached to a lateral extremity of said lower airfoil, a pair of upper major airfoils spaced from one another, the inner transverse extremity of one of them being attached to the upper portion of said structure in a manner whereby said 'upper airfoil extends in a direction away from the other of said alrmils, .1 the-domgitudinal-noriial. planes of said iateral extremity said transverse extremity 's'ubstantiallyspaced from one another; said airplanejbeing-characterized by the absence of anyother major airfoil within the volume thealongitudinal normal planes passlngthrmigh the lateral extremities of said iowei uirfoil. 5 1 i comprising a lower major airwfoil' astructure whose lower portion is attached the lateralextremity of said lower airfoil a pair of upper'major air-toils spaced from one another, the inner transverseextremity of one of them beattached to the'upper'portion of said structure in 'a manner whereby said upper airfoil 'exin a direction away from the other of said upper airfoils, the longitudinal-normal planes of said lateral extremity and said transverse extremity being substantially spaced from one another, said airplane being characterized by the absence of any other major airfoil within the volume bounded by the longitudinal normal planes passing through the lateral extremities of said lower airfoil, said lower portion extending below said lower airfoil and serving to support said airplane on a water surface.

6. An airplane'comprising a lower major airfoil, a pair of structures whose lower portions are interconnected by and bracingly attached to said lower airfoil at the latters lateral extremities, a pair of upper major' airfoils spaced from one another, the inner transverse extremity of one of said upper airfoils being attached to the upper portion of one of said structures, the inner transverse extremity of the other of said upper airfoils being attached to the upper portion of the other of said structures, the longitudinal-normal planes of said lateral and said transverse extremities being all substantially spaced from one another. a

'7. An airplane comprising a lower major airfoil, a pair of structures whose lower portions are interconnected by and bracingly attached to said lower airfoil at the latters lateral extremities, a

pair of upper major airfoils spaced from one an-v other, the inner transverse extremity of one of said upper airfoils being attached to the upper portion of one of said structures, the inner transverse extremity of the other of said upper airfoils being attached to the upper portion of the other of said structures, the longitudinal-normal planes of said lateral and said transverse extremities being all substantially spaced from one another, said lower portions extending below said lower airfoil and serving to support said airplane on a water surface.

8. A seaplane comprising a pair of structures spaced from one another, each having its maximum dimension in excess of its maximum lateral dimension, 9. pair of substantially cantilever-type -major upper airfoils, the root-portion of one of said upper airfoils being bracingly attached to the upper portion of one of said structures in a manner whereby said upper airfoil extends in a direction away from the other of said structures, the root-portion of the other of said upper airfoils being similarly related to the upper portion of said last mentioned structure, thus causing said upper airfoils to be spaced from one another, a major lower airfoil bracingly attached to the lower portion of said first mentioned struc-v ture, said airplane being characterized by the absence of any other major airfoil within the volume bounded by the longitudinal normal planes passing through the lateral extremities of saidairtoil, saidstructure being proportioned to permit their functioning as substantially exclusive supports for said upper airfoils, said lower portion extending below said lower airfoil-and serving to support said seaplane on the water.

9. A seaplane comprisinga pairiot structures spaced from one'another, each having its maximum vertical dimension in excess of its maximum lateral dimension, a pair of substantially cantilever-type major upper airfoils, the root-portion of one of said upper airfoils beingvbracingly attached to the upper portion of one of said struc tures in a manner whereby said upper-airfoil extends in a directionaway from the otherot said plane on the water structures, the root-portion of theother of said upper airfoils being similarly related to the upper said structures, said seaplane; beingcharacterz lb th bs n e. 0f n v fi r maj r a foi w t mt the.. me h und d b t ensi qeim normal planes passingthrough the lateral ex"- tre nitiesqoi' vs a id lowger airfoil, said structures be ing proportioned to permit their functioning as substantially;eigclusive supports for said upper airfoils, said lower portionsextending below said lower airfoil and serving tosupport said sea- 

